KR900002740B1 - Battery feeding circuit for exchanges - Google Patents

Abstract

A reference resistance is connected to each of the two inputs. AC and DC feedback are fed back to the two inputs with coupling capacitors via reference resistors and provide a desired AC terminating resistance and DC input resistance. A control signal reverses the polarity of signals to the inputs by a noiseless signal to the DC feedback. The AC signal on the input is differentially amplified so that the differential signal is distinguished from the unwanted common mode signal. The terminating resistance for each signal can be changed by altering the feedback ratios of the feeding resistor between both signals.

Description

Feeder circuit for exchange

1 is a conventional power supply circuit diagram.

2 is a power supply circuit diagram according to an embodiment of the present invention.

3 is an example of a reverse polarity control signal waveform for transmitting a noiseless reverse polarity signal from the circuit of FIG.

4 is a power supply circuit diagram according to another embodiment of the present invention.

5 and 6 are opening views of the basic configuration of the power supply circuit according to the present invention.

The present invention relates to an internal termination reverse-feedback circuit for supplying talk current or supervisory current to a subscriber line or trunk line of an exchange.

The power supply circuit according to the present invention has a function of supplying a call current to a subscriber or a relay line, transmitting a voice signal to the line and terminating the voice signal from the line, as well as transmitting a polarity-reversal signal. do.

The exchange has a feed circuit for supplying talk current to the telephone. The main functions required for this feeder circuit are as follows.

(i) supply of talk current and / or supervisory current; (ii) transmission of voice signals to the telephone line and reception of voice signals from the telephone line; (iii) termination of the telephone line to the received voice signals; In the power feeding circuit of the prior art, respective circuits are required for performing each of these functions. Therefore, many parts are required, and the feeder circuit becomes large and complicated, which increases the manufacturing cost.

In addition, one of the components, the electronic inductor circuit, has a high impedance for a common mode signal (a longitudinal signal), so that a harmful phase signal in a telephone line cannot be terminated to a low resistance ground. In addition, there is a disadvantage in that the weight is increased and the packing density is poor because an LC filter circuit is required when the noiseless reverse polarity is required.

Capacitance and inductance elements in the LC filter circuit make it difficult to configure the power supply circuit as an integrated circuit.

Accordingly, it is an object of the present invention to provide an improved power feeding circuit capable of performing the above functions in a compact configuration.

According to the basic aspect of the present invention, a first reference resistor connected to a first line, a second reference resistor connected to a second line, and a gain and sum of 1 for supplying a talk current and a voice signal to the first line A first amplifier having a function and having an input stage connected to a first DC amplifier, an AC differential amplifier and an audio signal source, having a suitable DC gain and summation function, and also having a first line and DC control signal. A first direct current (DC) amplifier having an input connected to the generating circuit, an AC differential amplifier having an appropriate AC gain, and having an input terminal connected to the first line and the second line through a coupling capacitor; And a gain and summing function of 1 for supplying a talk current and a voice signal to the second line, and an input terminal connected to the second DC amplifier, an AC differential amplifier, and a voice signal source. Having a high and a second amplifier, and a suitable DC gain and summation function that, and also the exchange appointed power supply circuit including a second direct current (DC) amplifier having an input terminal coupled to the second line is provided.

According to another aspect of the present invention, an AC signal appearing between the first and second lines is fed back to the first and second reference resistors provided to each of the first and second lines through an AC feedback path. In addition, since the DC voltage is fed back on the first and second lines irrespective of the first and second reference resistors by DC feedback, a predetermined AC termination resistance and a predetermined DC feed resistance are realized thereby. A feed circuit for the exchange is provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a power supply circuit for an exchange of the present invention will be described in detail with reference to the accompanying drawings.

Before describing preferred embodiments, a conventional power supply circuit will be described with reference.

Referring to FIG. 1, a reverse polarity feeder circuit is shown.

In FIG. 1, 21b of 21a is an electronic inductor circuit, 22 is a transformer, 23 is a contact of a reverse polarity relay, 24 is a filter circuit and A and B are lines connected to a telephone.

This feeder circuit has separate circuits for each of its functions.

That is, the electronic inductor circuits 21a and 21b serve to supply talk current and / or supervisory current. That is, the talk current flows from the ground G to the line B through the resistor R _4b and the transistor TR _1b and is also fed back from the line A to the power source-V _BB through the transistor TR _1b and the resistor R _4a .

The value of the talk current is determined by the ratio of resistors R _1b and R _2b (also the ratios of resistors R _1a and R _1b ).

Transformer 22 has the function of transmitting and receiving voice signals from a call line as well as terminating call lines for voice signals.

The reverse polarity relay 23 has a function of transmitting a reverse polarity signal.

Filter circuit 24 is used for noise-free reverse polarity and is also added when feeder circuits are employed in public telephones that require noise-free reverse polarity for signal charging.

5 is a basic configuration opening diagram of the present invention.

In FIG. 5, line A and line B are connected to a subscriber line or trunk line.

The power feeding circuit of FIG. 5 realizes the AC feedback function for the AC signal on the A and B lines and the DC feedback function for the DC voltage on the A and B lines separately by a pair of DC feedback circuit and the AC feedback circuit.

을 갖는 증폭기(10_A또는 10_a)를 각각 포함하는 DC 궤환회로를 1_A및 1_B, 두 캐패시터들 20_A및 20_B와 증폭율

을 갖는 증폭기 21을 포함하는 궤환 회로 2, 가변전압원들 30_A및 30_B를 포함하는 역극성 제어신호 발생회로 3, 가입자 선에 음성신호를 송출시키기 위한 발생기 4, 증폭율 +1을 갖는 두개의 버퍼증폭기를 5_A및 5_B, 그리고 두 급전 저항(또는 기준저항)R_FA및 R_FB를 포함한다.That is, in FIG. 5, the power feeding circuit has an amplification factor.

_A DC feedback circuit comprising an amplifier (10 _A or 10 _a ) having a respectively 1 _A and 1 _B , two capacitors 20 _A and 20 _B and amplification factor

A feedback circuit 2 comprising an amplifier 21 having an amplifier 21, a reverse polarity control signal generator circuit 3 comprising variable voltage sources 30 _A and 30 _B , a generator 4 for transmitting a voice signal to the subscriber line, two having an amplification factor +1 The buffer amplifiers include 5 _A and 5 _B and two feed resistors (or reference resistors) R _FA and R _FB .

The number N of DC feedback circuits and the number M of AC feedback circuits are constants for determining the DC equivalent feed resistance R _EF and the AC termination resistor R _Dr.

The mutual relationship between them is as follows.

R _EF = R _F × N

R _DT = R _F × M × 2

Where R _F is the resistance value of the feed resistors R _FA and R _FB .

The characteristics of the circuit of FIG. 5 are as follows.

First, in this circuit, the predetermined DC equivalent feed resistance value R _EF and the predetermined AC termination resistance value R _DT are DC positive feedback to the feed resistances R _FA and R _FB to control the equivalent DC resistance value and AC resistance value of the feed resistance. And means for causing AC positive feedback.

Secondly, two DC feedback circuits are provided independently for each of the A and B lines.

This configuration can lower the supply voltage of the operational amplifier used in the circuit.

As a result, it is possible to employ a booster line without the need for an operational amplifier that withstands high pressure.

Third, the response signal, the charging signal, etc. can be sent out. The voltage on the A and B lines may be controlled by the reverse polarity signal.

Fourthly, the AC signals on A and B are amplified differentially, thereby canceling the differential signals, i.e., the voice signal and the in-phase signal, i.e., the harmful induction signal. Thus, the termination resistance for each signal can be different by varying the feedback ratio of the feed resistance between the two signals.

As a result, a commercial signal that is harmful to the power supply circuit may be terminated as low resistance values, that is, power supply resistors R _FA and R _FB , and the audio signal may be terminated as terminal resistance value R _DT .

6 shows an opening of the modified form of FIG. 5 according to the present invention. In this form, the AC feedback circuit 2 'is different from that in FIG.

That is, in FIG. 6, the AC feedback circuit 2 'comprises two summing amplifiers 22A and 22B provided for the A and B lines.

2 shows an embodiment derived from the basic configuration shown in FIG. 5 according to the present invention.

In FIG. 2, line A and line B are connected to a subscriber line or trunk line.

The received voice signal V _r is input to the A and B lines. This power feeding circuit of FIG. 2 is configured up and down symmetrically in FIG. 2 by the power feeding circuit for the A line and the power feeding circuit for the B line.

The call current can be supplied to the operational amplifier Q _5c line A, whose output terminal is connected to line A via the feed resistor (or reference resistor) R _F1 . Line A control voltage is input to the non-inverting input terminal of operational amplifier Q _a through terminal T _a and two resistors R _c1 and R _f1 .

The outgoing speech signal V _s is input to the connection point of the resistors R _c1 and R _f1 through the capacitor C _s1 .

Line A is connected to the non-inverting input terminal of operational amplifier Q _a and line B is connected to its inverting input terminal through capacitor C _c1 and resistor R _s2 . The feedback resistor R _f2 is connected between the inverting input terminal and the output terminal of the operational amplifier Q _a . The configuration of the power feeding circuit for the B line is the same. This feed circuit includes operational amplifier Q _b , feed resistor R _f2 , five resistors R _c2 , R _f3 , R _f4 , R _s3 and R _s4, and two capacitors C _s2 and C _c2 . The difference is that in the feeder circuit for line B, line B is connected to the non-inverting input terminal of the operational amplifier via resistor R _s3 , while line A is connected to its inverting input terminal via capacitor C _c2 and resistor R _s4 . will be.

Terminal T _b is provided for receiving the B line control voltage.

The correlation between the values of the components in this power supply circuit is as follows.

R _c1 , R _{c2 =} R _c

R _s1 to R _s4 = R _s

R _f1 to R _f4 = R _f

R _F1 , R _F2 = R

C _s1 C _s2 = C _s

C _c1 , C _c2 -C _c

Terminal resistance values for the values of resistors and capacitors for example, a voice signal V _r received example, as described in detail later R _DT is 600ohm, the equivalent feeding resistance R _EF is a ground resistance for 200ohm and statues induction signal is 50ohm Is selected to be.

2 illustrates an operation mode of a circuit as follows.

On the call terminating resistance R _DT, call line for terminating the voice signal V _r is received from the line call current and the monitoring current to a call line from the power source to supply the equivalent feeding resistance R _EF, statue induced signal R _c Termination resistance value R _CT (or ground resistance value), etc., is generally set to some nominal values by the exchange system. The feeder circuit of FIG. 2 must therefore be designed to realize these nominal values. In this example, the feed circuit is designed such that, for example, the terminal resistance value R _DT is 500 ohms, the equivalent feed resistance value R _EF is 200 ohms, and the feed resistance value R _CT is 50 ohms.

First, with regard to the termination of the voice signal V _r received from the telephone line, the power supply circuit of the present invention feeds the feed resistance to R _F1 and R _F2 by positive feedback of the received voice signal V _r, thereby reducing the low resistance ( Although the feed resistors R _F1 and R _F2 having 50 ohms) are used, a predetermined termination resistance value R _DT (600 ohms) can be realized.

That is, the impedances of capacitors C _c1 , C _c2 , C _s1 and C _s2 can be neglected compared to resistors R _s and R _f .

This is because its impedance with respect to the signal frequency of the received voice signal V _r is sufficiently small. Thus fed back to the operational amplifier Q _a and Q _b is the feed part of the received voice signal V _r, by operating as a positive phase amplifier circuit for receiving a voice signal V _r to the in-phase resistors R _F1 and R _F2. As a result, the termination resistance value R _DT for the received voice signal V _r becomes larger than the feed resistance value R _F. The terminating resistor R _DT is expressed as follows.

As is apparent from equation (1), the terminal resistance value R _DT is larger than the feed resistance value R _F. If R _DT and R _F are given, then R _s and R _f can be found in (1).

Then, in order to increase the toll-erance of the in-phase signal on the telephone line such as undesirably induced current, the in-phase induction signal V _c is not fed back to the feed resistances R _F1 and R _F2 in the feed circuit of the present invention. Therefore, the in-phase induction signal V _c is grounded through the feed resistors R _F1 and R _F2 . Accordingly, the feed resistances R _F1 and R _F2 having low resistance values become the ground termination resistance value R _{CT as} they are.

That is, if the impedances of capacitors C _c1 and C _c2 can be neglected compared to the resistance values R _s and R _f for the inphase induced signal V _c input to the A and B lines, the operational amplifiers include Q _a or Q _b . Each circuit acts as a differential amplifier, and the in phase induction signal V _c is canceled in each differential amplifier circuit. Therefore, the output signals corresponding to the inphase induction signal V _c do not appear at each output terminal of the operational amplifiers Q _a and Q _b . As a result, in effect, the in-phase induction signal V _c is the same as that which is grounded through the feed resistors R _f1 and R _F2 .

The terminal resistance value R _CT for the inphase induction signal V _c is expressed as follows.

R _CT = R _F (2)

Therefore, if R _F is 50 ohm, the phase induction signal V _c 50 ohm is terminated to ground, so the resistance of the in-phase signal such as induction current is improved by this low ground termination resistance value.

Then, for the feed resistance values for supplying current to the A and B lines, in this feed circuit, the DC voltage on the telephone line is fed back to the feed resistors by DC positive feedback, thereby reducing the resistance value (e.g., 50 ohms). Despite the use of low feed resistances, a predetermined equivalent feed resistance value (eg, 200 ohms) is obtained.

That is, the operational amplifiers Q _a and because of DC feedback loop of Q _b may be the same as the opening by the capacitors C _c1 and C _c2 operational amplifiers Q _a and Q _b acts as a voltage follower circuit for the voltage . Thus, the output voltages of the operational amplifiers Q _a and Q _b are equal to the input voltage applied to their non-inverting input terminals.

In this case, the equivalent feeding resistance for the A line and the equivalent feeding resistance R _EFA values for the B track _EFA R represents the following:

This in the equivalent feeding resistance R _EFA and R _EFA has terminals T _a, and since the calculation on the basis of the voltage of T _b, terminals T _a and the equivalent feed resistance as the change of control voltage to be applied to T _b sikyeojum R _EFA It is possible to vary the voltage on the A and B lines while keeping the and R _EFB constant.

Accordingly, the power supply circuit is capable of transmitting a polar signal Sikkim station by varying the control voltage on the terminals T _a and T _b.

That is, the voltage polarity on the A and B lines is reversed by the voltage polarity inversion on the terminals T _a and T _b , whereby the reverse polarity signal is sent out to the communication line. In this case, the properties in reverse polarity are quite the same as in normal polarity. This is because the feed circuits of the A and B lines are composed of perfect symmetry.

The fact, for example, shows that it is possible to a noiseless polarity reverse signal sent out easily by the seamless type opposite polarity control voltage as shown in FIG. 3 on the terminals T _a and T _b.

A third terminal for sending a noiseless polarity reverse signal to turn _a T and shows an example of the control voltage waveforms on the T _b.

In FIG. 3, the abscissa represents the voltage level on the terminals T _a and T _b and the ordinate represents the time, the tangent is the voltage waveform on terminal T _a , and the solid line is the voltage waveform on terminal T _b .

Finally, the transmission of the audio signal to the A and B lines will be described.

The output speech signal Vs is input to the non-inverting input terminals of the operational amplifiers Q _a and Q _b through the capacitors C _{s 1} and C s ₂ and the resistors R _f1 and R _f3 .

Transmission across the load resistance R _e between line A and B when the impedances of capacitors C s ₁ , C s ₂ , C _c1 and C _c2 for the frequency of the outgoing speech signal Vs are small enough to be negligible compared to other resistors The voice signal voltage V _t is expressed as follows.

If the voice signal voltage V _{t to} be transmitted and each resistance value of the resistance are given, the value of the voice signal voltage V _s to be input can be obtained from equation (4).

Although the preferred embodiments have been described so far, many modifications and variations are possible within the scope of the invention. 4 shows another such embodiment according to the present invention. In the feeding circuit of FIG. 2, if the talk current or the monitoring current supplied from the feeding circuit is large, it is impossible to supply the entire current from the operational amplifiers Q _a and Q _b .

The circuit of FIG. 4 can be modified to supply a larger current using a power booster. In Fig. 4, the output voltage of the operational amplifier Q _a is input to the feed resistor R _F1 through a power booster circuit 41 including the PNP transistor TR _a1 and the NPN transistor TR _a2 . In the same way, the output voltage of the operational amplifier Q _b is input to the feed resistor R _F2 through the power booster circuit 42, thereby supplying current to the A and B lines.

Claims (17)

The first and second reference resistance values R _FA and R are provided for each of the first and second lines through the differential amplification path by the AC feedback in which an AC signal appearing between the first and second lines A and B. _FB ; R _F1 , R _F2 ), and a direct current voltage on the first and second lines is thereby independently fed back to the first and second reference resistance values for each line by means of a direct current feedback. A feed circuit for exchanges characterized in that a predetermined AC termination resistance value and a predetermined DC feed resistance can be realized. 2. A feeder circuit for an exchange according to claim 1, characterized in that the direct current feedback is carried out by first and second direct current feedback circuits (1A, 1B) provided for each of the first and second lines. 2. A feeder circuit as claimed in claim 1, characterized in that the AC feedback is carried out by one differential amplifier (21) which is provided in common for the first and second lines. 2. A feeder circuit as claimed in claim 1, characterized in that the AC feedback is carried out by first and second differential amplifiers (22A, 22B) provided for each of the first and second lines. The first and second reverse polarity control circuits T _a , T _c1 , R _f1 ; T _b , T _c2 , R for inputting the reverse polarity control signal to the first and second DC feedback circuits. _f3 ), wherein the feeder circuit for the exchange is capable of transmitting a reverse polarity signal to the first and second lines. 6. The power supply circuit for a switch according to claim 5, wherein the noise-free reverse polarity signal can be transmitted by smoothly inverting the polarities of the first and second reverse polarity control signals. 2. The circuit of claim 1, further comprising a circuit (-V _s , C _{s 1} ; V _s , C _{s 2} ) for supplying an outgoing speech signal for the first and second reference resistance values, whereby the first and second A feeder circuit for an exchange, characterized by the ability to send audio signals to a track. 2. The feeder circuit of claim 1, wherein the AC feedback and the DC feedback are performed by a pair of operational amplifiers (Q _a , Q _b ) provided for the first and second lines. 6. The exchanger of claim 5, wherein the AC feedback, the DC feedback, and the reverse polarity control are performed by a pair of operational amplifiers Q _a and Q _b provided for the first and second lines. Feeding circuit. The first reference resistance value R _F1 connected to the first line A, the second reference resistance value R _F2 connected to the second line B, and the first input terminal are connected to the first line. A first amplifier Q _a for supplying a pass current for the first line and a second amplifier Q for supplying a talk current for the second line by connecting a first input terminal to a second input terminal. _b ), a first capacitive component C _c2 for coupling the second input terminal and the second line of the first amplifier, and a second input terminal for coupling the second input terminal and the second line of the first amplifier. 2. A feeder circuit for an exchanger comprising a capacitive component (C _c1 ). 11. The feeder circuit of claim 10, wherein the first and second amplifiers are operational amplifiers. 11. The feeder circuit of claim 10, wherein the first input terminals of the first and second amplifiers are non-inverting input terminals, and the second input terminals are inverting input terminals. 13. The first and second amplifiers of claim 12, wherein the first and second amplifiers act as voltage follower circuits for direct current voltages on the first and second lines, whereby the DC voltage is applied to the first and second reference resistance values by DC positive feedback. And the first and second amplifiers act as an AC positive feedback circuit for the voice signal V _r received between the first and second lines, whereby the voice signal received is reduced by AC positive feedback. And the first and second amplifiers do not respond to the normal signal (V _c ) and are thereby configured to terminate the in-phase signal to ground through the first and second reference resistance values. Characteristic feeder circuit for exchange. 11. The method of claim 10, wherein the first reverse polarity control signal is serially connected to the first input terminal of the first amplifier, and the second reverse polarity control signal is connected to the first input terminal of the second amplifier and further comprises first and second reverse polarity. And a reverse polarity signal can be sent to the first and second lines by controlling the control signals. The power supply circuit for exchange according to claim 14, wherein the noise-free reverse polarity signal can be transmitted by smoothly inverting the polarity of the first and second reverse polarity control signals. 11. The apparatus of claim 10, further comprising a circuit (-V _s , C _s ; V _s , C _{s 2} ) for inputting an outgoing speech signal between the first input terminals of the first and second amplifiers. A feeder circuit for a switch, characterized in that it can be sent to the first and second lines. 11. The feeder circuit of claim 10, wherein the circuits of the first and second lines are fully symmetrical.

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